The present invention relates to the incorporation of a lipid-enriched hydrophilic lotion on the body facing material of disposable absorbent articles, such as diapers, training pants, adult incontinence products, under pants, and feminine care products, and the like. More particularly, the present invention relates to improving skin health via enhancement of skin barrier function by the delivery of lipids and humectants of a hydrophilic lotion from the body facing material of absorbent articles to the skin.
The stratum corneum is the outer-most layer of the skin and is responsible for regulating skin water levels and functioning as a barrier against chemicals and other stressors found in the environment. The complex arrangement of lipids in the intercellular space of the stratum corneum is responsible for the establishment of normal barrier function. Multi-layered structures of cholesterol, ceramides, and fatty acids, as well as some other minor lipids, provides the major barrier to the transport of hydrophillic substances into the or through the skin. The link between the barrier function and skin health is apparent from the skin inflammation caused by lipid extraction from the skin.
Skin barrier can be damaged due to a number of mechanisms. Physical abrasion, for example caused by the repeated rubbing of abrasive materials, such as absorbent tissues or wipes, on the skin, strips away layers of the skin and thus damages skin barrier. Biological fluids, such as urine, feces and vaginal secretions, may contain a variety of components that can damage skin barrier. Examples of these components include proteases, lipases, and bile acids. Once the skin barrier is compromised, these components, in addition to other constituents of biological fluids, can initiate or exacerbate skin inflammation.
Diaper dermatitis, for example, is a genre of skin conditions that, in large part, originate from impaired barrier function. Impairment of the skin barrier can result from a variety of factors, including; increased skin hydration due to the occlusion of the skin caused by diapers, enzymatic skin damage due to fecal and urinary enzymes, and from physical damage imparted by wiping with a wet wipe.
Excessive hydration also has a negative impact on skin barrier. The hydration level of diapered skin, for example, may reach between five to ten times that of undiapered skin. Frequent contact of diapered skin with urine may also contribute to increased skin hydration. Increased skin hydration disrupts skin lipid organization in the stratum corneum. This disruption may increase-the skin permeability of irritants from feces and urine, thus increasing the risk of skin inflammation.
Diapered skin is normally cleansed several times a day with wipes utilizing solutions containing surfactants. The surfactants can extract lipids from the stratum corneum or disorganize the lipid structure within the stratum corneum, thereby decreasing the barrier function. The wipe material can cause physical damage to the skin and thus lead to decreased barrier function.
Typically, barrier creams, lotions and ointments are used to provide an artifical hydrophobic barrier on the skin. These products typically contain mineral oils, petrolatum and silicones that are heavy, greasy to the touch, and are typically used to treat, rather than prevent skin irritation.
Disposable absorbent articles such as diapers, training pants, adult incontinence products, absorbent under pants, and feminine care products have been used to absorb body fluids and leave the skin dry. Disposable absorbent articles of this type generally comprise a liquid impermeable back sheet member, an absorbent core or assembly, and a liquid permeable bodyside liner. It is the bodyside liner or other body facing material that comes into contact with the wearer""s skin. While the body facing material is made of a soft compliant material, it can abrade the skin during use and may not leave the skin completely dry and free of the bodily fluids, such as solid or semi-solid waste, the absorbent article is trying to absorb. During frequent insults of bodily fluids and frequent use of disposable absorbent articles, the skin can become so abraded as to appear red and be sore to the touch.
To reduce skin irritation and abrasion, additive formulations can be applied to the body facing material such that, in use, the additive formulation either provides lubricity thereby reducing abrasive contact, or leaves the body facing material and is deposited on the skin where it can soothe the skin.
Once deposited on the skin, these additive formulations provide a skin benefit by occluding the skin surface due to the hydrophobic waxes present in the formulation. Thus, these formulations provide a short-term benefit by providing an artificial barrier, even though the underlying stratum corneum is still damaged.
To date, these additive formulations have been liquids or oil based and typically from petroleum (lipophilic materials) based semi-solids or oil based solids at room temperature. The liquid or oil based semi-solid type of formulations require a high amount of formulation added to the body facing material to deliver the benefit of reduced skin irritation and redness because these formulations absorb into a body facing material, leaving less on the surface to provide the benefit.
The oil based solid formulations can be applied heated (slightly above the melting point of the formulation) to the surface of a body facing material thereafter resolidifying the formulation on the surface(s) of the body facing material where the formulation is readily available for transfer to the users skin to protect the skin from or prevent further irritation and redness in an efficient cost-effective manner. However, since these formulations are lipophilic, it is sometimes difficult to incorporate hydrophilic or water soluble surfactants, cosmetic materials or active ingredients.
Thus, there is a need for a formulation that is basically hydrophilic that can be applied to a body facing material of a disposable absorbent article which will transfer sufficient formulation to protect, maintain, and recover skin barrier function and thus protect the skin from or prevent further irritation and redness in an efficient cost-effective manner.
It has now been discovered that a skin barrier enhancing disposable absorbent articles can be made applying, on the outer surface of the body facing material, a melted hydrophilic composition comprising a hydrophilic solvent, a high molecular weight polyethylene glycol, a fatty alcohol (C14-C30 or greater), a humectant, an oil-in-water emulsifying surfactant having an HLB range greater than 7, a sterol or sterol derivative, and a natural fat or oil, and thereafter resolidifying the composition to form a distribution of a melted lipid-enriched hydrophilic composition on the outer surface of the body facing material. Because the hydrophilic composition is a solid at room temperature and rapidly solidifies after application, it has less tendency to penetrate and migrate into the body facing material. Compared to body facing material treated with liquid formulations, this leaves a greater percentage of the added solid lotion composition on the surface of the body facing material where it can contact and transfer to the user""s skin to provide a benefit. Furthermore, a lower add-on amount can be used to deliver the same benefit at a lower cost because of the efficient placement of the composition substantially at the surface of the body facing material of the absorbent articles.
Hence, in one aspect, the present invention is a hydrophilic composition comprising from about 10 to about 90 weight percent hydrophilic solvent, from about 5 to about 95 weight percent high molecular weight polyethylene glycol (preferably having a molecular weight of about 720 or greater), from about 1 to about 30 weight percent of a C14 to C30 or greater fatty alcohol, from about 0.5 to about 30 weight percent of humectant, from about 1 to about 20 weight percent emulsifying surfactant having an HLB range greater than 7, from about 0.1 to about 10 weight percent of sterol or sterol derivative, and from about 0.1 to about 30 weight percent of natural fats or oils. The hydrophilic composition may have a melting point from about 30xc2x0 C. to about 100xc2x0 C. and a process viscosity of greater than 50 centipoise. The composition may also have a penetration hardness of from about 5 millimeters to 360 millimeters.
In another aspect, the present invention is a body facing material wherein the outer surface of the body facing material have solidified deposits of a hydrophilic composition comprising from about 10 to about 90 weight percent hydrophilic solvent, from about 5 to about 95 weight percent high molecular weight (defined as a solid at room temperature) polyethylene glycol (preferably having a molecular weight of about 720 or greater), from about 1 to about 30 weight percent of a C14 to C30 or greater fatty alcohol, from about 0.5 to about 30 weight percent of humectant, from about 1 to about 20 weight percent emulsifying surfactant having an HLB range greater than 7, from about 0.1 to about 10 weight percent of sterol or sterol derivative, and from about 0.1 to about 30 weight percent of natural fats or oils. The hydrophilic composition may have a melting/freezing point of from about 30xc2x0 C. to about 100xc2x0 C. and a process viscosity of greater than 50 centipoise. The composition may also have a penetration hardness from about 5 millimeters of penetration to 360 millimeters of penetration.
In another aspect, the present invention is a method of making a body facing material in an absorbent article comprising: (a) heating a composition comprising a hydrophilic solvent, high molecular weight polyethylene glycol, a fatty alcohol, a humectant, an emulsifying surfactant having an HLB range greater than 7, a sterol or sterol derivative, and a natural fat or oil to a temperature above the melting point of the composition, causing the composition to melt; (b) uniformly applying the melted composition to the outer surface of the body facing material web in spaced-apart deposits; and (c) resolidifying the deposits of the melted composition. The hydrophilic composition may have a melting point of from about 30xc2x0 C. to about 100xc2x0 C.